# [seqfan] Re: Polyominoes (A000105, A000988, A001168) - offset problem

Jean-Luc Manguin jean-luc.manguin at unicaen.fr
Wed Jun 24 17:59:13 CEST 2020

```Again, I refer to the definition of polyominoes (https://en.wikipedia.org/wiki/Polyomino) : "A polyomino is a plane geometric figure formed by joining one or more equal squares edge to edge."

"One or more", this is clear... (unless someone can prove that zero is more than one)

I agree that they should cross-refer (and that is another reason to put the same offset value).

JLM

----- Mail original -----
De: "Fred Lunnon" <fred.lunnon at gmail.com>
À: "seqfan" <seqfan at list.seqfan.eu>
Envoyé: Mercredi 24 Juin 2020 17:51:37
Objet: [seqfan] Re: Polyominoes (A000105, A000988, A001168) - offset problem

A000105 with offset = 0  is correct as it currently stands:
there is 1 empty polyomino with  #cells = 0 .

My preference would be to attach an extra 1 at the front of both
A000988 and A001168 , and edit to  offset = 0.

All three should cross-refer to the others; and similar remarks
may apply to related sequences, such as A030228.   NJAS ?

Fred Lunnon

On 6/24/20, Jean-Luc Manguin <jean-luc.manguin at unicaen.fr> wrote:
> Hello,
>
> Everytime I edit a sequence, I receive justified remarks about my
> non-respect of some rules, although of course this non-respect is not done
> by purpose.
>
> In return, I would like to find in OEIS a care about coherence ; this
> example needs (IMO) a little correction :
> - A000105 has an offset = 0
> - A000988 and A001168 have offset = 1
>
> These three sequences give the number of polyominoes (free, one-sided, and
> fixed) and as it is written in the dedicated page in Mathworld, [
> https://mathworld.wolfram.com/Polyomino.html |
> https://mathworld.wolfram.com/Polyomino.html ] , there is no polyomino with
> zero cell ; then I would be pleased to see A000105 with offset = 1, which
> seems much more logical. Of course I could edit this sequence (I did not
> try, I guess I can), but I prefer to mention this in the list.
>
> Thank you, dear editors, for your attention to this message.
> Have a nice day and a happy St John !
>
> JL Manguin
>
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>

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